The present invention relates to a epichlorohydrin-based flexible elastomer composition.
More specifically, it relates to elastomer compositions based on epichlorohydrin homopolymer or copolymer and ethylene oxide having improved properties compared with the presently known elastomers of this type, particularly with respect to their resistance to pressurized hydraulic fluids at temperatures exceeding 120.degree. C.
It is known that epichlorohydrin-based elastomers have excellent chemical and physical properties, and in particular a resistance to hydraulic fluids better than that of elastomers which are considered to be resistant thereto, such as nitrile rubbers, acrylic rubbers and neoprenes, a resistance to ozone equivalent to that of the best of the three aforementioned elastomers and an excellent heat resistance.
However, the presently known epichlorohydrin-based elastomer compositions do not make it possible to obtain elastomers which, at temperatures above 120.degree. C., have elastic properties and a resistance to tearing which are completely satisfactory, or particularly when they have to be used in the presence of oil.
The presently known elastomer compositions generally comprise an epichlorohydrin homopolymer or copolymer, a reinforcing filler constituted by carbon black, acid acceptors such as zinc stearate and minium, a protection agent such as nickel dibutyl dithiocarbamate, whilst they are vulcanized at about 150.degree. C. by vulcanizing agents such as thiourea derivatives.
Such compositions have the disadvantage of containing toxic constituents, such as lead and thiourea derivatives, whilst they are also difficult to handle because they stick to the roller during rolling. Moreover, they corrode the moulds during press vulcanization.